package network;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

public class UdpEchoServer {
    private DatagramSocket socket = null;
    
    public UdpEchoServer(int port) throws SocketException {
        socket = new DatagramSocket(port);
    }
    
    public void start() throws IOException {
        System.out.println("服务器启动");
        while (true) {
            DatagramPacket requestPacket = new DatagramPacket(new byte[4090],4090 );
            socket.receive(requestPacket);
            String request = new String(requestPacket.getData(),0, requestPacket.getLength());
            String response = process(request);
            DatagramPacket responsePack = new DatagramPacket(response.getBytes(), response.getBytes().length,
                    requestPacket.getSocketAddress());
            socket.send(responsePack);
            System.out.printf("[%s:%d] req=%s, resp=%s\n", requestPacket.getAddress().toString(),
                    requestPacket.getPort(), request, response);
        }

    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        UdpEchoServer server = new UdpEchoServer(9090);
        server.start();
    }

}
